Security of capsular fixation: small-versus large-hole plate-hepatic lenses

Hydrophobic acrylic and plate-haptic silicone intraocular lens implantation in diabetic patients

PURPOSE

To compare the capsular and uveal reaction after implantation of a plate-haptic silicone intraocular lens (IOL) (C11UB, Chiron) and a hydrophobic acrylic (AcrySof MA60, Alcon) IOL in diabetic patients.

SETTING

Moorfields Eye Hospital and St. Thomas' Hospital, London, United Kingdom.

METHODS

Thirty-five diabetic patients were recruited consecutively and randomly assigned to have implantation of either of the 2 IOLs. The percentage area of posterior capsule opacification (PCO), anterior capsule contraction (ACC), and postoperative inflammatory indices (flare and cells) were assessed objectively at 2 to 3 weeks, 6 months, and 1 year. Between-group and within-group analyses were conducted using the Student t test or Mann-Whitney test and Friedmann test, respectively.

RESULTS

Between-group analysis showed the percentage area of PCO was significantly greater in patients with plate-haptic silicone IOLs at 6 and 12 months (P = .002). At 6 months, ACC was significantly greater in the plate-haptic group (P = .04), but the difference was not significant at 12 months. There was higher flare in the hydrophobic acrylic IOL group than in the plate-haptic silicone IOL group at 2 to 3 weeks (P = .08). Within-group analysis showed that over the follow-up period, the plate-haptic silicone group, but not the hydrophobic acrylic group, had a progressive increase in PCO (P = .003). In the hydrophobic acrylic group, but not the plate-haptic silicone group, there was a significant reduction in the mean anterior chamber flare value (P = .01). There was no significant difference in visual acuity or contrast sensitivity at any postoperative visit.

CONCLUSION

In diabetic patients, hydrophobic acrylic IOLs can lead to an increased flare in the early postoperative period but they seem to be more favorable than plate-haptic silicone IOLs because the latter lead to more PCO.

Surface calcification of silicone plate intraocular lenses in patients with asteroid hyalosis

PURPOSE

To report three cases in which a silicone-plate lens was explanted because of whitish deposits on the posterior optic surface.

DESIGN

Observational case series with clinicopathological correlation.

PATIENTS AND METHODS

In the three instances, the deposits were observed at least 2 years after uneventful cataract surgery. All of the patients had unilateral mild asteroid hyalosis in the concerned eye. After explantation of the lenses, gross and light microscopic analyses were performed. The posterior optic surfaces of the lenses also underwent scanning electron microscopy coupled with energy dispersive x-ray spectroscopy for analysis of the elemental composition of the deposits.

RESULTS

Gross and light microscopic analyses revealed well-demarcated areas of whitish deposits on the posterior optic surface of the lenses, as well as multiple pits caused by Neodymium:yttrium aluminum garnet laser treatments. The deposits formed an amorphous layer with a "crustlike" appearance, which was confirmed by scanning electron microscopy. X-ray spectroscopy analyses demonstrated the composition of the deposits to be similar to hydroxyapatite.

CONCLUSIONS

The material opacifying the lenses was probably derived from the asteroid bodies or from a similar process that results in this vitreous condition. We were unaware of this association between asteroid hyalosis and late postoperative dystrophic calcification of silicone lenses.

Late anterior traumatic subluxation of a circular in-the-bag intraocular lens associated with lack of posterior capsule opacification

We report a case of traumatic subluxation of a circular poly(methyl methacrylate) intraocular lens (IOL) 5 years after surgery. Slitlamp examination revealed the lack of epithelial cells or fibrosis in the intact capsule bag. Trauma was minor, and no other complication was found in the eye and orbit. The subluxated IOL was easily relocated in the bag with a hook, revealing the poor capsule sealing. Among the factors ensuring the fixation of IOLs placed in the bag after continuous curvilinear capsulotomy are sealing of the anterior and posterior capsules and proliferation of epithelial cells from the equator of the bag.

Evaluation of 3 modern single-piece foldable intraocular lenses: clinicopathological study of posterior capsule opacification in a rabbit model

PURPOSE

To assess the development of posterior capsule opacification (PCO) with 3 modern single-piece foldable intraocular lenses (IOLs) in a histopathological study and to compare the potential preventive effects of the IOL design and biomaterial in retarding PCO.

SETTING

Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, Medical University of South Carolina, Charleston, South Carolina, USA.

METHODS

Thirty-one rabbit eyes were randomly operated on with phacoemulsification and implantation of 3 single-piece foldable lenses: a hydrophilic acrylic design, the Rayner Centerflex 570H (n = 11); a hydrophobic acrylic design, the Alcon AcrySof SA30AL (n = 10); and a silicone large-hole plate design, the Staar AA-4203VF (n = 10). Central PCO (CPCO), peripheral PCO (PPCO), and Soemmering's ring formation were evaluated 3 weeks after surgery using the Miyake-Apple posterior photographic technique. Histological sections of each globe were prepared to document capsular bag status and performance of IOL geometry.

RESULTS

The acrylic IOLs (Centerflex and AcrySof) had lower CPCO and PPCO scores than the silicone plate IOL (P <.05). There was no significant difference in Soemmering's ring formation among the 3 models. Pathological evaluations revealed effective blockage of migrating lens epithelial cells (LECs) at the site of the truncated optic edge of the Centerflex and AcrySof IOLs, even in the presence of large amounts of retained/regenerative cortical material.

CONCLUSIONS

The AcrySof IOL has a hydrophobic surface and the Centerflex a hydrophilic surface, but no correlation to these characteristics could be identified. The single-piece AcrySof optic geometry created a clear-cut barrier effect equal to that of its 3-piece predecessor. The anatomic profile of the Centerflex IOL shows the same characteristics. The optics of both acrylic lenses have square truncated edges that functionally block ingrowth of migrating LECs toward the central visual axis, leaving clear posterior capsules. The square optic edge was an appropriate geometric configuration to create a barrier effect. There was no effect of the biomaterial on PCO prevention.

Anterior capsule opacification: correlation of pathologic findings with clinical sequelae

OBJECTIVE

To evaluate the degree of anterior capsule opacification (ACO) in human eyes obtained postmortem containing various rigid and foldable posterior chamber intraocular lens (PC-IOL) designs and compare the findings with clinical sequelae of capsular shrinkage.

DESIGN

Comparative autopsy tissue study with clinicopathologic correlations.

MATERIALS

Three hundred formalin-fixed human eyes containing the following PC-IOL styles were analyzed: (1) one-piece polymethyl methacrylate (PMMA) optic-PMMA haptic (n = 50), one-piece silicone-plate IOL, with large (2) or small (3) fixation holes (n = 35), (4) three-piece PMMA optic-Prolene haptic (n = 50), (5) three-piece acrylic optic-PMMA haptic (n = 55), three-piece silicone optic with PMMA (6) or polyimide (7) haptics (n = 30), and (8) three-piece silicone optic-Prolene haptic (n = 80) lenses.

TESTING

The eyes were sectioned in the equatorial plane for gross examination of the capsular bag from a posterior view. The cornea and iris were then excised for evaluation from an anterior view.

MAIN OUTCOME MEASURES

ACO was scored in each eye from 0 to IV, according to the degree/area of capsule opacification. Capsulorrhexis size and IOL decentration were measured with calipers.

RESULTS

The overall differences among the IOL groups regarding the three parameters were significant (ACO score: P < 0.001; capsulorrhexis diameter: P = 0.036; IOL decentration: P = 0.012). Mean ACO scores were highest with the large- and small-hole one-piece silicone-plate lenses (2.543 +/- 0.950) and lowest with the three-piece acrylic optic-PMMA haptic lenses (0.600 +/- 0.710). Of 10 cases of capsulorrhexis phimosis observed in the study, 7 cases were associated with three-piece silicone optic-Prolene haptic lenses, which also presented the highest mean decentration (0.375 +/- 0.601 mm).

CONCLUSIONS

Our results confirm previous histopathologic observations that the rate of ACO is the lowest with acrylic lenses and higher with plate-haptic silicone IOLs. Nevertheless, clinical sequelae of capsular shrinkage are also very important with three-piece silicone optic-Prolene haptic designs. Thus, IOL material and design are significant factors in the development of ACO, but they ultimately also influence the clinical presentation of capsular shrinkage.

Collamer intraocular lens: clinical results from the US FDA core study

PURPOSE

To assess the safety and efficacy of the Staar Collamer intraocular lens (IOL) 1 year postoperatively.

SETTING

Fifteen private ophthalmology practices geographically distributed throughout the United States.

METHODS

Six hundred eighty-six cases with a mean age of 72.1 years were enrolled in a 2-phase U.S. Food and Drug Administration (FDA) clinical study of the Collamer IOL implanted during phacoemulsification for cataract removal. The 12 month follow-up comprised data from 502 cases.

RESULTS

Twelve months postoperatively, 96.2% of all cases and 95.6% without preexisting pathology achieved 20/40 or better best corrected visual acuity. Both results were better than FDA Grid values. No persistent sight-threatening complications, IOL dislocations, or IOL removals were reported.

CONCLUSIONS

Results show that the Collamer IOL is safe and effective for use in small incision cataract surgery.

Delayed posterior dislocation of silicone plate-haptic lenses after neodymium:yag capsulotomy

We report 4 cases of posterior dislocation of silicone plate-haptic intraocular lenses (iols) into the vitreous cavity occurring a mean of 16 months after neodymium:YAG laser posterior capsulotomy. In each case, no peripheral capsule defect was observed at the time of laser capsulotomy or at subsequent follow-ups. One case was treated with sulcus implantation of a 3-piece IOL, with the plate-haptic IOL left in the vitreous cavity. The other cases were managed with vitrectomy (2 pars plana, 1 anterior) to remove the plate-haptic lens with subsequent sulcus placement of a 3-piece IOL. Patients should be informed that posterior dislocation is an infrequent but possible complication of these lenses and may occur months and even years after implantation or laser capsulotomy.

Effect of large positioning holes on capsule fixation of plate-haptic intraocular lenses

PURPOSE

To compare the centration and fixation of silicone plate-haptic intraocular lenses (IOLs) with different-sized positioning holes.

SETTING

Eye Clinic of the Johannes Gutenberg-University Mainz, Mainz, Germany.

METHODS

In a prospective randomized study, 51 Chiroflex C10 and 56 Chiroflex C11 IOLs were implanted under standardized conditions by the same surgeon. The IOL position was documented at the end of surgery and by retroillumination on the first day and 5 months postoperatively. The positioning-hole area was evaluated by ultrasound biomicroscopy (50 MHz) 5 months postoperatively.

RESULTS

One day postoperatively, no IOL in either group was decentered more than 1.0 mm. After 5 months, 33% of the C10 and 42% of the C11 IOLs were decentered between 0.5 and 1.0 mm, and 11% of the C10 and 8% of the C11 IOLs were decentered more than 1.0 mm (maximum 1.23 mm and 1.41 mm, respectively). Up to the first postoperative day, 20% of the C10 and 22% of the C11 lenses were rotated more than 15 degrees. At 5 months, an additional 15% of the C10 and 19% of the C11 lenses were rotated. Ultrasound biomicroscopy showed no tissue or capsule adhesion in the holes in most cases (85% C10 group; 71% C11 group). No difference was statistically significant.

CONCLUSIONS

Larger positioning holes did not prevent IOL decentration or rotation; thus, this IOL design appears unsuitable for correcting astigmatism. Because tissue in the positioning hole was rare with both lens types, it is doubtful that enlarged plate-haptic perforations will prevent IOL luxation into the vitreous cavity after capsulotomy.

Posterior dislocation of a plate-haptic silicone intraocular lens with large fixation holes

We present a patient who had uneventful phacoemulsification with in-the- bag implantation of a silicone plate-haptic posterior chamber intraocula r lens (IOL) with 1.15 mm fixation holes. Six months after a neodymium: YAG laser capsulotomy, the IOL spontaneously dislocated posteriorly. A pars plana vitrectomy was performed, the IOL was explanted, and a 3-piece loop-haptic IOL was implanted in the ciliary sulcus. Eight weeks after surgery, best corrected visual acuity was 20/20.

Comparative evaluation of plate haptic lenses with smaller and larger positioning holes

PURPOSE

To evaluate the visual outcome, intraoperative problems and postoperative complications of plate haptic intraocular lenses with smaller foot plate positioning holes and larger holes.

METHODS

Fifty eyes of 50 patients underwent clear corneal phacoemulsification with implantation of either small hole plate haptics (25 eyes) or large hole plate haptic lenses (25 eyes). The intraoperative complications were noted and the postoperative parameters were evaluated on the first day, 1 week, 1 month, 3 months, 6 months and 12 months. These included the best corrected visual acuities, intraocular lens (IOL) decentring, diameter of anterior capsulorhexis and posterior capsule opacification.

RESULTS

The mean duration of follow-up was 14.8+/-2.1 months in the group with the small foot plate positioning holes (Chiron C10UB) lens and 15.6+/-3.2 months in the group with the large feet plate positioning holes (Chiron C11UB) lens. The was no significant difference in the visual acuities of the two groups. The mean IOL decentring was 0.42+/-0.28 mm in the C10UB lenses and 0.24+/-0.10 mm in the C11UB lenses (P = 0.05). The mean diameter of the anterior capsulorhexis was 4.68+/-0.23 mm in the former, while it was 4.21+/-0.68 mm in the latter (P = 0.0027). The posterior capsule opacification was significantly increased in the C11UB group (P = 0.0298). Neodymium : yttrium aluminium garnet (Nd: YAG) laser capsulotomy was required in 8% of the C10UB group, compared to 28% in the C11UB group.

CONCLUSION

Results are similar with the two types of plate haptic lenses. The lenses with larger holes have a significantly higher posterior capsule opacification and more anterior capsulorhexis contracture, although the IOL decentring is less with these lenses.

Postoperative intraocular lens rotation: a randomized comparison of plate and loop haptic implants

OBJECTIVE

To compare the postoperative rotation of plate and loop haptic implants of spherical power to ascertain the optimal design appropriate for toric intraocular lenses (IOLs).

DESIGN

Randomized, controlled trial.

PARTICIPANTS

Forty-eight patients attending for routine cataract surgery by phacoemulsification.

METHOD

Patients with cataract as the only ocular disease were randomly implanted with plate or loop haptic implants after uncomplicated phacoemulsification. The baseline position of the IOL was determined from a video frame acquired at the conclusion of surgery. Postoperative IOL position was documented using digital retroillumination images at 2 weeks and 6 months after surgery. Capsular fusion patterns were recorded using slit-lamp biomicroscopy. Correlation of IOL rotation with axial length, capsular contraction, and fusion was attempted.

MAIN OUTCOME MEASURES

Early IOL rotation, occurring between surgery and 2 weeks after surgery, was graded as mild (<10 degrees), moderate (10 degrees < to <30 degrees), or severe (>30 degrees) by a semiobjective online comparison of the images. Late IOL rotation, occurring between 2 weeks and 6 months, was measured more precisely using software developed specifically for the study.

RESULTS

Twenty-three patients were allocated the loop haptic and 25 the plate haptic IOL. The groups were comparable for demographic variables and numbers of patients excluded from analysis (P > 0.05). Five (24%) of 21 of plate haptic IOLs underwent severe early rotation compared to 2 (9%) of 22 loop haptics (P = 0.36). The median late rotation was 6.8 degrees for loop haptics compared to 0.6 degrees for plate haptics (P = 0.0073). Between 2 weeks and 6 months, anticlockwise rotation had occurred in 16 (89%) of 18 loop haptic IOLs compared to 11 (52%) of 21 plate haptic IOLs (P = 0.0081).

CONCLUSIONS

Plate haptic IOLs show greater rotational stability than do loop haptics made from polypropylene once capsular fusion has taken place. Loop haptics invariably rotate anticlockwise after 2 weeks.

Fixation elements on plate intraocular lens: large positioning holes to improve security of capsular fixation

OBJECTIVE

This study aimed to evaluate in rabbit eyes the effects of large positioning holes in one-piece silicone plate-haptic intraocular lenses (IOLs) with respect to security of capsular bag fixation. Mechanical strength of capsular fixation is correlated with the histologic findings of regenerating lens material and fibrous tissue ingrowth through the positioning holes on silicone plate IOLs, comparing capsules implanted with large-hole style plate IOLs to fellow capsules implanted with small-hole style plate IOLs.

DESIGN

The study design was a prospective, randomized, experimental study.

PARTICIPANTS

A total of 40 fellow capsular bags from 20 New Zealand white rabbits were examined. Capsules implanted with conventional small-hole silicone plate IOLs were used as the control in all pairs of fellow capsules.

INTERVENTION

Phacoemulsification and implantation of a silicone plate IOL with small positioning holes in one eye and implantation of a silicone plate IOL with large positioning holes in the fellow eye were measured. All rabbits were killed at 2 months. The force required to extract the IOLs from the capsular bag was measured. All capsular bags underwent histopathologic analysis.

MAIN OUTCOME MEASURES

Extraction force measurements and histopathologic examination, comparing capsules implanted with small-hole plate IOLs with fellow capsules implanted with large-hole plate IOLs, were measured.

RESULTS

The large-hole style IOL required significantly more force to extract from the capsular bag compared to the conventional small-hole style (P = 0.003). Histologically, proliferating lens epithelial material and fibrous tissue were observed growing through all of the large positioning holes (synechia formation) but not through any of the small positioning holes.

CONCLUSIONS

Silicone plate IOLs with large positioning holes become affixed more firmly within the capsular bag compared to conventional small-hole plate IOLs. These findings suggest that large holes in silicone plate IOLs allow for superior capsular bag fixation. This should reduce the rates of decentration and dislocation.